Influence of the power quality instrument class on the accurate of the PQ measurement.

Abstract

In order to an accurate interpretacion of the measure results, it has been established an International Standard. The IEC 61000-4 defines the methods for measurement and interpretation of the results. This Standard is applied for power quality parameters in 50/60 a.c. power supply systems. For each relevant type of parameter is described a measurement method. Every method makes possible to obtain reliable, repeatable and comparable results regardless of the compliant instrument being used and regardless of its environmental conditions. During a measurement campaign, we conect the measurement device, for usually a week, on the PCC (Point of Common Coupling) of one factory. It is necessary to take into account the appropriate measurement methods for a successful performance. But if we use different instruments of measure at the same time, we will find differences between theirs results. It is worthwhile asking if the differences between instruments are negligible or not. In order to look for an answer to this question we have made different tests and measurements at the Electromagnetic Compatibility Laboratory and at the PCC of one factory with three different instruments: one of class A (Topas 1000) and two of B class (Unilyzer 812 and Memobox 300 smart). Previously we have compared two Unilazers 812 and also two Mamobox 300 Smart The results and conclusions of this comparison will be presented in this paper.